kernel: lib: Add convert functions for hex strings and binary arrays

Move duplicate hex2bin and add bin2hex function so that application can
use the functions and avoid code duplication.

Signed-off-by: Joakim Andersson <[email protected]>

include/sys/util.h

@@ -18,6 +18,7 @@
 
 #include <zephyr/types.h>
 #include <stdbool.h>
+#include <stddef.h>
 
 /* Helper to pass a int as a pointer or vice-versa. */
 #define POINTER_TO_UINT(x) ((uintptr_t) (x))
@@ -122,6 +123,56 @@ static inline s64_t arithmetic_shift_right(s64_t value, u8_t shift)
 	return (value >> shift) | (sign_ext << (64 - shift));
 }
 
+/**
+ * @brief      Convert a single character into a hexadecimal nibble.
+ *
+ * @param[in]  c     The character to convert
+ * @param      x     The address of storage for the converted number.
+ *
+ *  @return Zero on success or (negative) error code otherwise.
+ */
+int char2hex(char c, u8_t *x);
+
+/**
+ * @brief      Convert a single hexadecimal nibble into a character.
+ *
+ * @param[in]  c     The number to convert
+ * @param      x     The address of storage for the converted character.
+ *
+ *  @return Zero on success or (negative) error code otherwise.
+ */
+int hex2char(u8_t x, char *c);
+
+/**
+ * @brief      Convert a binary array into string representation.
+ *
+ * @param[in]  buf     The binary array to convert
+ * @param[in]  buflen  The length of the binary array to convert
+ * @param[out] hex     Address of where to store the string representation.
+ * @param[in]  hexlen  Size of the storage area for string representation.
+ *
+ * @return     The length of the converted string, or 0 if an error occurred.
+ */
+size_t bin2hex(const u8_t *buf, size_t buflen, char *hex, size_t hexlen);
+
+/*
+ * Convert hex string to byte string
+ * Return number of bytes written to buf, or 0 on error
+ * @return     The length of the converted array, or 0 if an error occurred.
+ */
+
+/**
+ * @brief      Convert a hexadecimal string into a binary array.
+ *
+ * @param[in]  hex     The hexadecimal string to convert
+ * @param[in]  hexlen  The length of the hexadecimal string to convert.
+ * @param[out] buf     Address of where to store the binary data
+ * @param[in]  buflen  Size of the storage area for binary data
+ *
+ * @return     The length of the binary array , or 0 if an error occurred.
+ */
+size_t hex2bin(const char *hex, size_t hexlen, u8_t *buf, size_t buflen);
+
 #endif /* !_ASMLANGUAGE */
 
 /* KB, MB, GB */

lib/os/CMakeLists.txt

@@ -8,6 +8,7 @@ zephyr_sources(
   crc8_sw.c
   crc7_sw.c
   fdtable.c
+  hex.c
   mempool.c
   rb.c
   thread_entry.c

lib/os/hex.c

@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2019 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <stddef.h>
+#include <zephyr/types.h>
+#include <errno.h>
+#include <sys/util.h>
+
+int char2hex(char c, u8_t *x)
+{
+	if (c >= '0' && c <= '9') {
+		*x = c - '0';
+	} else if (c >= 'a' && c <= 'f') {
+		*x = c - 'a' + 10;
+	} else if (c >= 'A' && c <= 'F') {
+		*x = c - 'A' + 10;
+	} else {
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+int hex2char(u8_t x, char *c)
+{
+	if (x <= 9) {
+		*c = x + '0';
+	} else  if (x >= 10 && x <= 15) {
+		*c = x - 10 + 'a';
+	} else {
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+size_t bin2hex(const u8_t *buf, size_t buflen, char *hex, size_t hexlen)
+{
+	if ((hexlen + 1) < buflen * 2) {
+		return 0;
+	}
+
+	for (size_t i = 0; i < buflen; i++) {
+		if (hex2char(buf[i] >> 4, &hex[2 * i]) < 0) {
+			return 0;
+		}
+		if (hex2char(buf[i] & 0xf, &hex[2 * i + 1]) < 0) {
+			return 0;
+		}
+	}
+
+	hex[2 * buflen] = '\0';
+	return 2 * buflen;
+}
+
+size_t hex2bin(const char *hex, size_t hexlen, u8_t *buf, size_t buflen)
+{
+	u8_t dec;
+
+	if (buflen < hexlen / 2 + hexlen % 2) {
+		return 0;
+	}
+
+	/* if hexlen is uneven, insert leading zero nibble */
+	if (hexlen % 2) {
+		if (char2hex(hex[0], &dec) < 0) {
+			return 0;
+		}
+		buf[0] = dec;
+		hex++;
+		buf++;
+	}
+
+	/* regular hex conversion */
+	for (size_t i = 0; i < hexlen / 2; i++) {
+		if (char2hex(hex[2 * i], &dec) < 0) {
+			return 0;
+		}
+		buf[i] = dec << 4;
+
+		if (char2hex(hex[2 * i + 1], &dec) < 0) {
+			return 0;
+		}
+		buf[i] += dec;
+	}
+
+	return hexlen / 2 + hexlen % 2;
+}

subsys/bluetooth/mesh/shell.c

@@ -13,6 +13,7 @@
 #include <ctype.h>
 #include <zephyr.h>
 #include <sys/printk.h>
+#include <sys/util.h>
 
 #include <shell/shell.h>
 #include <settings/settings.h>
@@ -205,37 +206,6 @@ static const struct bt_mesh_comp comp = {
 	.elem_count = ARRAY_SIZE(elements),
 };
 
-static u8_t hex2val(char c)
-{
-	if (c >= '0' && c <= '9') {
-		return c - '0';
-	} else if (c >= 'a' && c <= 'f') {
-		return c - 'a' + 10;
-	} else if (c >= 'A' && c <= 'F') {
-		return c - 'A' + 10;
-	} else {
-		return 0;
-	}
-}
-
-static size_t hex2bin(const char *hex, u8_t *bin, size_t bin_len)
-{
-	size_t len = 0;
-
-	while (*hex && len < bin_len) {
-		bin[len] = hex2val(*hex++) << 4;
-
-		if (!*hex) {
-			len++;
-			break;
-		}
-
-		bin[len++] |= hex2val(*hex++);
-	}
-
-	return len;
-}
-
 static void prov_complete(u16_t net_idx, u16_t addr)
 {
 	shell_print(ctx_shell, "Local node provisioned, net_idx 0x%04x address "
@@ -395,7 +365,8 @@ static int cmd_static_oob(const struct shell *shell, size_t argc, char *argv[])
 		prov.static_val = NULL;
 		prov.static_val_len = 0U;
 	} else {
-		prov.static_val_len = hex2bin(argv[1], static_val, 16);
+		prov.static_val_len = hex2bin(argv[1], strlen(argv[1]),
+					      static_val, 16);
 		if (prov.static_val_len) {
 			prov.static_val = static_val;
 		} else {
@@ -422,7 +393,7 @@ static int cmd_uuid(const struct shell *shell, size_t argc, char *argv[])
 		return -EINVAL;
 	}
 
-	len = hex2bin(argv[1], uuid, sizeof(uuid));
+	len = hex2bin(argv[1], strlen(argv[1]), uuid, sizeof(uuid));
 	if (len < 1) {
 		return -EINVAL;
 	}
@@ -727,7 +698,8 @@ static int cmd_net_send(const struct shell *shell, size_t argc, char *argv[])
 		return 0;
 	}
 
-	len = hex2bin(argv[1], msg.data, net_buf_simple_tailroom(&msg) - 4);
+	len = hex2bin(argv[1], strlen(argv[1]),
+		      msg.data, net_buf_simple_tailroom(&msg) - 4);
 	net_buf_simple_add(&msg, len);
 
 	err = bt_mesh_trans_send(&tx, &msg, NULL, NULL);
@@ -940,7 +912,8 @@ static int cmd_net_key_add(const struct shell *shell, size_t argc, char *argv[])
 	if (argc > 2) {
 		size_t len;
 
-		len = hex2bin(argv[3], key_val, sizeof(key_val));
+		len = hex2bin(argv[3], strlen(argv[3]),
+			      key_val, sizeof(key_val));
 		(void)memset(key_val, 0, sizeof(key_val) - len);
 	} else {
 		memcpy(key_val, default_key, sizeof(key_val));
@@ -981,7 +954,8 @@ static int cmd_app_key_add(const struct shell *shell, size_t argc, char *argv[])
 	if (argc > 3) {
 		size_t len;
 
-		len = hex2bin(argv[3], key_val, sizeof(key_val));
+		len = hex2bin(argv[3], strlen(argv[3]),
+			      key_val, sizeof(key_val));
 		(void)memset(key_val, 0, sizeof(key_val) - len);
 	} else {
 		memcpy(key_val, default_key, sizeof(key_val));
@@ -1141,7 +1115,7 @@ static int cmd_mod_sub_add_va(const struct shell *shell, size_t argc,
 
 	elem_addr = strtoul(argv[1], NULL, 0);
 
-	len = hex2bin(argv[2], label, sizeof(label));
+	len = hex2bin(argv[2], strlen(argv[2]), label, sizeof(label));
 	(void)memset(label + len, 0, sizeof(label) - len);
 
 	mod_id = strtoul(argv[3], NULL, 0);
@@ -1189,7 +1163,7 @@ static int cmd_mod_sub_del_va(const struct shell *shell, size_t argc,
 
 	elem_addr = strtoul(argv[1], NULL, 0);
 
-	len = hex2bin(argv[2], label, sizeof(label));
+	len = hex2bin(argv[2], strlen(argv[2]), label, sizeof(label));
 	(void)memset(label + len, 0, sizeof(label) - len);
 
 	mod_id = strtoul(argv[3], NULL, 0);

subsys/bluetooth/shell/bt.c

@@ -18,6 +18,7 @@
 #include <string.h>
 #include <sys/printk.h>
 #include <sys/byteorder.h>
+#include <sys/util.h>
 #include <zephyr.h>
 
 #include <settings/settings.h>
@@ -229,21 +230,6 @@ static struct bt_conn_cb conn_callbacks = {
 };
 #endif /* CONFIG_BT_CONN */
 
-static int char2hex(const char *c, u8_t *x)
-{
-	if (*c >= '0' && *c <= '9') {
-		*x = *c - '0';
-	} else if (*c >= 'a' && *c <= 'f') {
-		*x = *c - 'a' + 10;
-	} else if (*c >= 'A' && *c <= 'F') {
-		*x = *c - 'A' + 10;
-	} else {
-		return -EINVAL;
-	}
-
-	return 0;
-}
-
 static int hexstr2array(const char *str, u8_t *array, u8_t size)
 {
 	int i, j;

subsys/net/l2/bluetooth/bluetooth_shell.c

@@ -25,21 +25,6 @@ LOG_MODULE_REGISTER(net_bt_shell, CONFIG_NET_L2_BT_LOG_LEVEL);
 #include <bluetooth/bluetooth.h>
 #include <bluetooth/hci.h>
 
-static int char2hex(const char *c, u8_t *x)
-{
-	if (*c >= '0' && *c <= '9') {
-		*x = *c - '0';
-	} else if (*c >= 'a' && *c <= 'f') {
-		*x = *c - 'a' + 10;
-	} else if (*c >= 'A' && *c <= 'F') {
-		*x = *c - 'A' + 10;
-	} else {
-		return -EINVAL;
-	}
-
-	return 0;
-}
-
 static int str2bt_addr_le(const char *str, const char *type, bt_addr_le_t *addr)
 {
 	int i, j;

subsys/testsuite/include/test_ecc_utils.h

@@ -64,16 +64,6 @@
 #include <tinycrypt/ecc.h>
 #include <test_utils.h>
 
-int hex2int(char hex);
-
-
-/*
- * Convert hex string to byte string
- * Return number of bytes written to buf, or 0 on error
- */
-int hex2bin(uint8_t *buf, const size_t buflen, const char *hex,
-	    const size_t hexlen);
-
 /*
  * Convert hex string to zero-padded nanoECC scalar
  */

tests/crypto/tinycrypt/src/ecc_dsa.c

@@ -66,6 +66,7 @@
 #include <tinycrypt/sha256.h>
 #include <test_utils.h>
 #include <test_ecc_utils.h>
+#include <sys/util.h>
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -109,7 +110,7 @@ int sign_vectors(TCSha256State_t hash, char **d_vec, char **k_vec,
 		string2scalar(exp_r, NUM_ECC_WORDS, r_vec[i]);
 		string2scalar(exp_s, NUM_ECC_WORDS, s_vec[i]);
 
-		msglen = hex2bin(msg, BUF_SIZE, msg_vec[i], strlen(msg_vec[i]));
+		msglen = hex2bin(msg_vec[i], strlen(msg_vec[i]), msg, BUF_SIZE);
 
 		/**TESTPOINT: Check if msg imported*/
 		zassert_true(msglen, "failed to import message!");
@@ -366,7 +367,7 @@ int vrfy_vectors(TCSha256State_t hash, char **msg_vec, char **qx_vec, char **qy_
 		exp_rc = res_vec[i];
 
 		/* validate ECDSA: hash message, verify r+s */
-		msglen = hex2bin(msg, BUF_SIZE, msg_vec[i], strlen(msg_vec[i]));
+		msglen = hex2bin(msg_vec[i], strlen(msg_vec[i]), msg, BUF_SIZE);
 
 		/**TESTPOINT: Check if msg imported*/
 		zassert_true(msglen, "failed to import message!");